Adaptive alien genes are maintained amid a vanishing introgression footprint in a sea squirt.

Human transport of species across oceans disrupts natural dispersal barriers and facilitates hybridization between previously allopatric species. The recent introduction of the North Pacific sea squirt, , into the native range of the North Atlantic sea squirt, , is a good example of this outcome. Recent studies have revealed an adaptive introgression in a single chromosomal region from the introduced into the native species.

Urban rendezvous along the seashore: Ports as Darwinian field labs for studying marine evolution in the Anthropocene.

Humans have built ports on all the coasts of the world, allowing people to travel, exploit the sea, and develop trade. The proliferation of these artificial habitats and the associated maritime traffic is not predicted to fade in the coming decades. Ports share common characteristics: Species find themselves in novel singular environments, with particular abiotic properties-e.